When was the last time you had a perfect framerate experience? Maybe the dips are more noticable at 60fps, than 30fps, but it's been a long time since I played something that I didn't notice a few drops here and there. Resogun has dips (even if hardly noticable, but more so when playing co-op), even Star Dust HD had some if I recall correctly (though very very rare to the point you'd still call it 'perfect').
With games, there are just too many factors that could blow the threshold of time required to calculate a frame. Take MGS2 for example; On the whole a flawless 60fps experience, yet there's this scene with around 100 soldiers standing there. If you threw a stun grenade into the crowd, the game would pretty much dip to nearly a complete halt as each of the hundred soldiers would react to the grenade being thrown with all the "!" popping up over their head. Quite comical actually, that part of the game.
If the dev states 60fps at 99%, it qualifies to me as perfect as any current shooter that offers a 60fps experience. BF4, all the CoD (which do have framerate drops here and there).
And the most sad thing is; even the games that target 30fps or were dropped to 30fps (after aiming to be 60fps) have drops too and rarely offer a "perfect" consistent framerate. Perhaps the tolerance level there is just higher because everything is more or less juddery, so a bit more juddery is less of an illusion breaker than having a perfect smooth experience with a few dips here and there.